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1、NetworksNetworksEGPRS EGPRS 相关参数介绍相关参数介绍BSC LEVELBSC LEVEL2 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials3 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsGTUGTGTUGTBSC LevelGPRS territory update guard time(GTUGT)Q3 name:terrUpdateGuardTimeGPRS Modification:Online Range:1.255(s)MML default:5 Descript
2、ion:With this parameter you set the timer,which must elapse between two subsequent territory updates.Related command(s):EEN,EEO Recommended value:default.Planning:Too high value causes low throughput(the time is too long to wait for triggering territory update),while too low value can generates high
3、 signaling.MNDLMNDL4 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsBSC LevelMaximum number of DL TBF(MNDL)Q3 name:PcuMaxNoDLtbfInCH Modification:Online Range:1 9 MML default:9 Description:With this parameter you define the maximum number of TBFs that a radio time slot can have in average,in a GPRS t
4、erritory,in the downlink direction.Related command(s):EEQ,EEO Recommended value:default.Planning:There is no any reason to reduce this paremeter from 9 to lower value.MNULMNUL5 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsMaximum number of UL TBF(MNUL)Q3 name:PcuMaxNoULtbfInCH Modification:Online R
5、ange:1 7 MML default:7 Description:With this parameter you define the maximum number of TBFs that a radio time slot can have in average,in a GPRS territory,in the uplink direction.Related command(s):EEQ,EEO Recommended value:default.Planning:There is not any reason to reduce this parameter from 7 to
6、 lower value.These parameters cannot have values higher than nine and seven,respectively.This restriction is brought about by the number of available timing advance indexes and USF values:the number of available USF values limits the number of UL TBFs to seven per timeslot;the number of available ti
7、ming advance indexes is 16 including both UL and DL TBFs,which means that the maximum number of UL TBFs being seven there can be at most nine DL TBFs.BSC LevelMNDLMNDL6 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsMaximum number of DL TBF(MNDL)Q3 name:PcuMaxNoDLtbfInCH Modification:Online Range:1 9
8、 MML default:9 Description:With this parameter you define the maximum number of TBFs that a radio time slot can have in average,in a GPRS territory,in the downlink direction.Related command(s):EEQ,EEO Recommended value:default.Planning:There is no any reason to reduce this paremeter from 9 to lower
9、value.BSC LevelCSUCSU7 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsFree TSL for CS upgrade(CSU)Q3 name:FreeTSLsCsUpgrade Modification:Online Range:0-10(s)MML default:4 Description:With this parameter you define a period following a GPRS upgrade during which the probability for a GPRS downgrade in
10、a BTS should be no more than 5%.Based on the given time and the size of a BTS(number of TRXs)the BSC defines a margin of idle TSLs that is required as a condition for starting a GPRS territory upgrade in the BTS.A GPRS upgrade may be done if the number of free TSLs in a BTS is at least equal to the
11、defined margin still after the upgrade.In the margin definition the BSC uses a table that is shown in GPRS territory upgrade of GPRS in BSC.Related command(s):EEM,EEO Recommended value:default BSC LevelFree TSL for CS upgrade(CSU)With this parameter you define a period following a GPRS upgrade durin
12、g which the probability for a GPRS downgrade in a BTS should be no more than 5%.Default value for the period length is 4 4 seconds.seconds.BSC LevelCSDCSD9 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsFree TSL for CS downgrade(CSD)Q3 name:FreeTSLsCsDowngrade Modification:Online Range:0-100(%)MML de
13、fault:95 Description:The parameter gives a target probability of TCH availability for circuit switched services in a BTS with GPRS territory.Based on the given probability and the size of a BTS(number of TRXs)the BSC defines a margin of idle TCHs that it tries to maintain free for the incoming circu
14、it switched TCH requests in the BTS.If the number of idle TCHs in the circuit switched territory of a BTS decreases below the defined margin a GPRS territory downgrade is started.In the margin definition the BSC uses a table that is shown in GPRS territory downgrade of GPRS in BSC.Related command(s)
15、:EEM,EEO Recommended value:default BSC LevelFree TSL for CS downgrade(CSD)That means that if we have 4TRXs/cell and at a certain moment we have a decreased number of TSLs for example the number of idle TSLs falls to 1 the associated probability of being free is 93%,less than the threshold(95%),that
16、means that a GPRS downgrade will be startedBSC LevelMEMORY_OUT_FLAG_SUM MEMORY_OUT_FLAG_SUM 11 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsMEMORY_OUT_FLAG_SUM(Parameter 046:0046)Value Meaning 0 Deactivates algorithm use.Default value(s):SX:3D Allowed values:0-7D The parameter is used to activate t
17、he MS Out of Memory exception procedure in RLC to reduce the number of MCSs used.BSC LevelRLCRLC确认模式控制参数确认模式控制参数 Acknowledgement Request GPRS Uplink Penalty GPRS Uplink Threshold GPRS Downlink Penalty GPRS Downlink Threshold EGPRS Uplink Penalty EGPRS Uplink Threshold EGPRS Downlink Penalty EGPRS Do
18、wnlink Threshold Description of EGPRS Downlink These parameters are used by the RLCacknowledgementalgorithmtodetermine how frequently the PCU pollsthe mobile station having a DL TBF inEGPRS mode.The PCU has a counter,which is incremented by one wheneveran RLC data block is transmitted for thefirstti
19、meorretransmittedpre-emptively.The counter is incrementedby(1+EGPRS_DOWNLINK_PENALTY)whenever a negatively acknowledgedRLC data block is retransmitted.Themobilestationispolledwhenthecounter exceeds the threshold value ofEGPRS_DOWNLINK_THRESHOLD.TSL Utilization BSC Level上行上行RLCRLC传送传送3131111114569212
20、223RLC data transmissionPacket Uplink ACK/NACKUSFTimePCUPCUMSMS1010111.111101001Bitmap(64 Blocks)Bitmap(64 Blocks)SSNPacket Control ACK/NACKPenaltyIncrementThresholdTotalTSL Utilization BSC Level上行上行RLCRLC传送传送 GPRS Uplink PENALTY3 GPRS uplink THRESHOLD22 PCU端对上行RLC的传送有个记数器，收到一个RLC块，就加1，到22后就会发出RLC的A
21、CK/NACK消息。如果中间有些RLC是重传，就会用3加而非1，以加快恶劣情况下的重传确认。这些详细的RLC重传机制，也给RLC的传送效率留了微调到最优化的余地。原理上，门限设的最大，中间传送的Poll和Ack也会少，如果无线环境非常好，将提高RLC传送速率，但是如果无线环境不好，就会加大停顿时间。相反调小了，也会稍微减少传送速度。GPRS与EGPRS有各自的RLC重传参数14 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials331311111111PenaltyIncrementThresholdTotal369101112131415161718
22、RLC data block retransmissionNew RLC data BlockRLC data block with pollPCUPCUPacket Downlink ACK/NACKTime1010111.111101001Bitmap(64 Blocks)Bitmap(64 Blocks)SSNMSMS下行下行RLCRLC传送传送TSL Utilization BSC Level下行下行RLCRLC传送传送 GPRS DOWNLINK PENALTY3 GPRS DOWNLINK THRESHOLD18 PCU端对下行RLC的传送有个记数器，传一个RLC块，就加1，到18
23、后就会发出poll指令，手机收到后就会发出RLC的ACK/NACK消息。如果中间有些RLC是重传，就会用3加而非1，以加快恶劣情况下的重传确认。16 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials上下行上下行TBF TBF 释放延迟释放延迟 If there is not any payload RLC/MAC block received,the TBF will not be released immediately,but it can be kept alive for a given time period.There are two m
24、odifiable parameters related to Delayed TBF feature among PRFILE parameters:DL_TBF_RELEASE_DELAY(0,1-5sec,def 1s)This parameter is used to adjust the delay in downlink TBF release.An appropriate delay time increases the system performance,since the possibly following uplink TBF can be established fa
25、ster,and frequent releases and re-establishments of downlink TBF can be avoided.UL_TBF_RELEASE_DELAY(0,1-3sec,def 0,5s)This parameter is used to adjust the delay in uplink TBF release.An appropriate delay time increases the system performance,since the possibly following downlink TBF can be establis
26、hed faster.Release Delay and BS_CV_MAX BSC Level18 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials上下行上下行TBF TBF 释放延迟释放延迟相对于普通的TBF 释放，在NOKIA 的PCU 中提供了TBF 释放延迟功能。通过PCU 中相关参数的控制，在正常需要进行TBF 释放的时刻，PCU 通过特定的机制把相应的TBF 再延续一段时间。参数名称046:0067 DL_TBF_RELEASE_DELAY046:0068 UL_TBF_RELEASE_DELAYTBF 释放延迟功能益处：a)由于延迟释
27、放，TBF 的建立可以通过PACCH 进行，加快TBF 建立的速度，b)上下行TBF的指配可以通过PACCH 实现，降低降低CCCH 上负荷；c)减少频繁TBF 建立、释放的可能性TBF 释放延迟功能负面影响：a)由于存在释放延迟，在一定程度上增加了PCU 负荷；b)PCU 在下行发送一些特定的数据块来实现TBF 延迟，某些手机可能无法正常识别并且响应，这样可能会增加由于手机无响应的TBF drop 次数c)该功能在上层不稳定，存在时延的情况下有效果，但是无论何种情况下，都需要上层应用（比如：WAP）的时延不能够超过PCU 中设置的释放时延，否则本功能不起作用。19 2005 Nokia V1
28、-Filename.ppt/yyyy-mm-dd/Initials上行上行TBF TBF 释放延迟原理释放延迟原理Nokia 上行TBF 延迟释放：PCU 通过延迟发送FAI=1 的上行数据包证实块来实现TBF 释放延迟。和正常情况下的TBF 释放比较，带来好处如下：普通上行TBF 释放：对于上行TBF，在手机发现数据将会发送完成的时候，手机会启动倒计数过程，在发送的每一个块中都包含一个CV 值告诉PCU 上行数据发送即将完成；在发送最后一个块的时候，CV0 通知PCU 数据发送完成，然后手机启动计时器，等待PCU 发送FAI=1 的控制块进行TBF 释放。UL TBF Release wit
29、h Extended UL TBF modeUL TBF Release with Extended UL TBF modeMSBSC/PCUData block with CV=0EUTM delay timer startsSchedule USF turn for MSUL dummy control blockSchedule USF turn for MSUL dummy control blockEUTM delay timer expiresPACKET UL ACK/NACK(FAI=1,Polling=YES)PACKET UL ACK/NACK(FAI=0,Polling=
30、NO)PACKET CONTROL ACKUL TBF terminatedData block with CV=1UL TBF extended stateShort description:Countdown procedure is ongoing.EUTM supporting mobile is allowed to recalculate CV during procedure,if it gets more data to send.PCU notices this by monitoring Block Sequence Number(BSN)and Countdown val
31、ue(CV)sent by MS.After receiving CV=0 block PCU starts UL extended state.It sends Packet Uplink Ack/Nack message to MS with no Final Ack Indicator(FAI)on,but acknowledging all received blocks.During UL extended state PCU schedules USFs for MS according adjustable scheduling rate parameter.If MS has
32、no new data to send it sends UL dummy control blocks on its sending turn.When UL extended state ends,according adjustable release delay parameter,PCU sends Packet Uplink Ack/Nack message to MS with Final Ack Indicator(FAI)on.UL TBF Schedule Rate ExtSchedule USF turn for MSUL dummy control blockMS do
33、es not continue TBFRelease Delay and BS_CV_MAX 20 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsUL TBF Release with Extended UL TBF modeUL TBF Release with Extended UL TBF modeShort description:Countdown procedure is ongoing.After receiving CV=0 block PCU starts UL extended state.It sends Packet Upl
34、ink Ack/Nack message to MS with no Final Ack Indicator(FAI)on,but acknowledging all received blocks.During UL extended state PCU schedules USFs for MS according adjustable scheduling rate parameter.If MS has no new data to send it sends UL dummy control blocks on its sending turn.When MS gets new da
35、ta to send during extended state,it sends UL data block with new BSN,and also new CV value when needed.Due BSN PCU knows that new UL LLC is to be sent by MS,and UL TBF continues as normally.UL TBF extended stateMSBSC/PCUData block with CV=0EUTM delay timer startsSchedule USF turn for MSData block wi
36、th new BSN and CVSchedule USF turn for MSUL dummy control blockEUTM delay timer stopped,TBF continuesPACKET UL ACK/NACK(FAI=0,Polling=NO)Data blockUL TBF Schedule Rate ExtMS continues data transfer on TBFRelease Delay and BS_CV_MAX 21 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials22 2005 Nokia V1-Fi
37、lename.ppt/yyyy-mm-dd/Initials下行下行TBF TBF 释放延迟原理释放延迟原理普通下行TBF 释放：在PCU发现发送最后一个数据块的时候，把其中的判断标志FBI置为1，告诉手机下行数据已经发送完成。同时PCU 侧也会启动相应的计时器，等待手机回对应的确认消息，进行正式的TBF释放流程。Nokia 下行TBF 延迟释放：23 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsGPRS GPRS 网络网络TBF TBF 释放延迟功能测试释放延迟功能测试为验证TBF 释放延迟功能在网络中实际使用效果，于 1123 选择 HG1B
38、7 BSC 进行相关测试。通过分别设置不同的参数组合并且针对相关的GPRS 业务进行测试，了解不同参数值对测试结果的影响。同时对比分析参数修改前和修改后的网络统计指标，掌握网络指标的变化趋势，为最终的优化参数选择提供有力的依据。在本次测试中，选用的参数组合情况如下：测试地点选择为：国宾、富豪酒店；进行的测试包括：PDP 激活、PING、FTP 下载、WAP 登录、图铃下载等。上行释放延迟下行释放延迟Case I0.51Case I11.5Case I1.5224 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/Initials修改修改TBF TBF 释放延迟后信令流
39、程分析释放延迟后信令流程分析启动正常释放流程启动正常释放流程开始开始TBF释放时延释放时延开始开始TBF 释放时延前释放时延前时延：T=07:247-05:452s25 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsFTP FTP 测试结果比较测试结果比较（每次各做（每次各做4 4次次FTP FTP 下载）下载）FTP下载应用层速率下载应用层速率(K bytes/s)3.603.773.791.943.843.420.001.002.003.004.005.006.0020051114豪富酒店.logNovember23 15_36-FUHAO(1
40、.5s).logNovember23 17_24-HAOFU-(2s).log20051122国宾酒店.logNovember23 11_32-GUOBING1(1.5s).logNovember23 19_24-GUOBIN(2s).logFTP下载下行平均时隙数量下载下行平均时隙数量3.03.03.01.93.02.90.00.51.01.52.02.53.020051114豪富酒店.logNovember23 15_36-FUHAO(1.5s).logNovember23 17_24-HAOFU-(2s).log20051122国宾酒店.logNovember23 11_32-GUOBI
41、NG1(1.5s).logNovember23 19_24-GUOBIN(2s).logDL:TBF=1UL:TBF=0.5DL:TBF=1.5UL:TBF=1DL:TBF=2UL:TBF=1.5值逐步增加结果分析：1。国宾由于测试环境问题，几次测试之间占用时隙数目不一致。2。从富豪酒店来看，随着延迟时间增加FTP 下载速率有一定提升。26 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsPING PING 测试结果比较测试结果比较（每次各做（每次各做4040次次PINGPING测试）测试）结果分析：对于PING 测试，从两个测试点大量的测试结果来看
42、，随值的增加，PING 时延也逐步增加。这说明对于PING 这种小业务，并且ping 的对端地址在本地时延本身就不明显的情况，该参数不起作用。造成ping时延增加的主要原因为释放时延长TBF 复用就越明显。ping平均时间平均时间1.331.421.441.381.401.510.001.002.003.0020051114豪富酒店.logNovember23 15_36-FUHAO(1.5s).logNovember23 17_24-HAOFU-(2s).log20051122国宾酒店.logNovember23 11_32-GUOBING1(1.5s).logNovember23 19_2
43、4-GUOBIN(2s).logDL:TBF=1UL:TBF=0.5DL:TBF=1.5UL:TBF=1DL:TBF=2UL:TBF=1.5值逐步增加27 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsTBF 掉线次数掉线次数RLC 层吞吐量层吞吐量下行下行TBF 占用时长占用时长BSC HG1B7 BSC HG1B7 指标统计指标统计00.511.522.533.51122112311221122TBF duration(ul)TBF duration(dl)由于延迟释放下行TBF 占用时间明显上升050001000015000200002500
44、030000350001122112311221122RCL Payload由于延迟释放下行TBF 占用时间明显上升01002003004005006007008001122112311221122PS CapacityTerritoryPeak sim tbf-ulUL-No rspPeak sim tbf-dlDL-No rsp由于某些终端支持原因，造成TBF 掉线次数上升28 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsTBF TBF 释放延迟参数测试总结释放延迟参数测试总结在PCU 发现将要进行上下行TBF 释放时，会根据相应的算法按设定
45、的参数延迟释放TBF对于FTP 测试，随参数值的变大，下载速率有一定程度提升对于PING，由于本身特点，参数不能够带来性能上提升。对于时延过大的情况，该功能不能够有效的进行处理。更长的时延参数意味着更多的负荷增加和指标的恶化。实际使用时需要在两者之间寻找一个良好的平衡。目前该参数最大值不能够超过5s.通过具体测试，目前上行1 秒，下行0.5 秒的释放时延是相对比较优化的推荐值。Practical experience of TBF release delay Practical experience of TBF release delay settingssettings DL releas
46、e delay 1s can be beneficial for RTT measurements Best values seen with 2-3 s DL release delay Extended UL release delay recommended to be 2-3 sec Rel-4 MS will use EUTM during UL TBF UL TBF release delay can be harmful for PoC if it is larger than 0.5 sec Rel-99 MS will use UL TBF delay if no concu
47、rrent DL TBFBSC LevelParameter RecommendationsParameter RecommendationsParameterParameter class/idBSS10.5+CD7(default)BSS11+CD5(recommendation)BSS11.5(Default)BSS11.5RecommendationDL_TBF_RELEASE_DELAY46/6703E8(1s)03E8(1s)03E8(1s)03E8(1s)UL_TBF_RELEASE_DELAY46/6801F4(0.5s)01F4(0.5s)01F4(0.5s)01F4(0.5
48、s)UL_TBF_RELEASE_DELAY_EXT46/71-07D0(2s)07D0(2s)07D0(2s)UL_TBF_SCHED_RATE_EXT46/72-4(80ms)4(80ms)4(80ms)BS_CV_MAX-6999EGPRS_UPLINK_PENALTY0001000100010001EGPRS_UPLINK_THRESHOLD0019001900190019EGPRS_DOWNLINK_PENALTY0001000100010001EGPRS_DOWNLINK_THRESHOLD0019001900190019Source:Veli-Pekka KetonenRelea
49、se Delay and BS_CV_MAX BSC LevelSEG LEVELSEG LEVEL31 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsGENAGENA32 2005 Nokia V1-Filename.ppt/yyyy-mm-dd/InitialsSEG LevelGPRS enabled(GENA)Q3 name:GPRSEnabled Modification:Online Range:Y/N MML default:N Description:With this parameter you define whether th
50、e GPRS capability is enabled in the BTS during the normal operation of the cell.Related command(s):EQV,EQO Recommended value:default Planning:The continuous coverage area can be limited by this parameter,but(E)GPRS mobiles will camp on those cells,which are selected by C1,C2 or C31/32 parameters(GPR